I guess just a last question from me: Does it seem necessary to you to replace filters every 6-12 months as manufacturers suggest? I have run filters for >2 years and cannot really discern any increased load on the fan motors, just listening for changes in motor sound. Nor can I sense any significant reduction in air flow, just feeling the air flow with my hand. I am asking as I am telling people not to replace the filters as often as manufacturers suggests - it is expensive and people might think that their purifiers do not work well after a filter is 6-12 months old.

Do you know why, apart from increased energy usage and perhaps fan wear and tear, one needs to replace filters as pressure increases? My understanding is that filter efficiency does not decrease but maybe I missed something. And I agree measuring the pressure drop is best, but just thinking for some DIY, at-home quick fix without any special tools, it might just make sense to check if the airflow is more or less the same.

Yeah perhaps. But on my purifiers there is at least one screen sorting out a lot of debris. And then I vacuum the filters every now and then. I guess one might notice if the airflow significantly reduces. I am running a test on mine to see how long they last. You have prompted me to get a new filter and later on just test how much air flow is reduced with the old filters - thanks for the inspiration. But I think one can safely run the home air filter for much longer than the 6-12 months suggested by manufacturers.

Great article, makes a lot of sense. It might make sense to launch towards commercial sectors first - there they are more interested in increasing air quality at low cost and low noise. Just realized that some hair salons have purifiers - I think there are lots of small hair particles floating around that I think you don't want to inhale.

On replacing filters: There is actually this study from the national labs that indicate filters hardly need replacement at all. I think it is even worse than razorblades that grow dull - filters last forever! It is a shame the torrent of marketing now has the public believing the filters need frequent replacement - that will be a hard myth to kill for a startup.

Just woke up to what you mention about optimization in HVAC installation, here in Sweden they mount ductwork components with something akin to TDC/TDF - it is literally easier than Lego! It is so fast I was blown away working with it. And no special tools required. Awesome podcast you did btw on Pigeon Hour!

On cause prioritization, is there a more recent breakdown of how more and less engaged EAs prioritize? Like an update of this? I looked for this from the 2024 survey but could not find it easily: https://forum.effectivealtruism.org/posts/sK5TDD8sCBsga5XYg/ea-survey-cause-prioritization 

Yes, this seems similar to how I feel: I think the major donor(s) have re-prioritized, but am not so sure how many people have switched from other causes to AI. I think EA is more left to the grassroots now, and the forum has probably increased in importance. As long as the major donors don't make the forum all about AI - then we have to create a new forum! But as donors change towards AI, the forum will inevitable see more AI content. Maybe some functions to "balance" the forum posts so one gets representative content across all cause areas? Much like they made it possible to separate out community posts?

A related issue I have actually encountered is something like "but you seem overqualified for this role we are hiring for". Even if previously successful people wanted to take a "less prestigious" role, they might encounter real problems in doing so. I hope the EA eco system might have some immunity to this though - as hopefully the mission alignment will be strong enough evidence of why such a person might show interest in a "lower" role.

I have never worked with fire plume models nor looked at that presentation, but have done some of the most advanced work on understanding wind conditions on the 2km-100km scale. What I know from that, probably quite similar work, is that there are so many parameters in these type of models to tweak the output. And that often, unfortunately, practice is to keep re-running models while tweaking until the output looks like the experimental results. I am not saying this happened here, I am just encouraging anyone looking into this to really pay attention to this, especially if making important decisions. If they do not explicitly and clearly say that the model results are a first-try, "no tweak" run, I would assume they have done tweaking and would consider the results not of sufficient quality to support conclusions.

What we did in the wind speed work I was involved in was to look at performance on statistically significant numbers of never-seen-before cases, really sitting on our hands and avoiding the temptation to re-run the simulations with more "realistic" model settings.

Btw Anam, with sample size exactly equal to 1 I wanted to let you know that your suggestions might have made a world of difference. Moreover, I think experimenting within safe limits with supplements might not be a bad idea. While my blood tests show I am not deficient in iron, I feel much better since exactly 1 week since starting iron supplements. Perhaps optimal iron intake is individual and/or there are energy boost gains to be had at increments some, or perhaps even all the way from the deficiency criteria all the way up to upper limits? I also include a gram of vit c per day along with my iron supplement and also try to keep this away from caffeine intake.